1. Field
An aspect of an embodiment of the present invention relates to a touch screen panel and a fabrication method thereof.
2. Description of Related Art
A touch screen panel is an input device into which a user can input his or her instruction by selecting instruction contents displayed on the screen of an image display device, etc., using a human hand or an object.
To this end, the touch screen panel is provided on the front face of the image display device to convert the contact position directly contacted by the human hand or the object into electrical signals. Therefore, the instruction contents selected on the contact position are accepted as input signals. The touch screen panel may replace a separate input device, such as a keyboard and a mouse, coupled to the image display device.
Types of the above described touch screen panel include a resistive type, a light sensitive type, a capacitive type, etc.
The capacitive type touch screen panel senses the change in capacitance that is formed between a conductive sense pattern and other neighboring sense patterns such as a ground electrode, etc., when it is touched by a human's hand or an object, thereby converting the contact position into electrical signals.
Here, in order to determine the contact position on the contact surface, the sense patterns include first sense patterns (X patterns) coupled in a first direction and second sense patterns (Y patterns) coupled in a second direction.
In the related art, the first and second sense patterns are disposed on different layers, respectively. In other words, for example, the first sense patterns are positioned on the lower layer, and the second sense patterns are positioned on the upper layer, wherein a dielectric layer is interposed therebetween.
However, when the sense patterns are formed on different layers, respectively, the surface resistance of the transparent conductive material (for example, ITO) used as the sense patterns is large so that the width of the coupling part coupling the sense patterns positioned on the same layer is large in order to reduce the surface resistance. In this case, the overlapped area between the coupling parts positioned on the upper and lower layers becomes large so that the parasitic capacitance becomes large, thereby degrading the sensitivity of the sense patterns.
Alternatively, the first and second sense patterns are positioned on the same layer, and they are coupled by forming separate coupling patterns through contact holes formed on the dielectric layer on the upper portion of the first or second sense patterns. Here, the coupling pattern is a metal material having a low resistance value.
For example, as in the related art, the coupling part of the first sense patterns is implemented with the transparent conductive material, and the coupling part of the second sense patterns crossing the coupling part of the first sense patterns is formed in a coupling pattern implemented with low-resistance metal material.
In other words, the first sense patterns are overlapped with the second sense patterns in the area where the coupling pattern is formed, and the width of the coupling pattern is minimized, thereby making it possible to reduce the effects of the parasitic capacitance generated from the overlapped area.
However, in this case, the coupling part coupling the second sense patterns is still formed of transparent conductive material with a high resistance value, the overlapped area between the sensing patterns is reduced, and the coupling pattern is positioned on the upper portion of the dielectric layer, having a disadvantage that it is weak against the static electricity applied from the outside.